Field of the Invention: The present invention relates to modified adducts of polyepoxide and polyoxyalkylenepolyamines to produce reaction products for use in cationic electrodeposition.
A serious problem associated with electrodeposition, as practiced industrially, is appearance defects in films. Such film defects include craters resulting from contamination due to dirt, oil and the like.
U.S. Pat. No. 4,423,166 describes an additive which can be added to a cationic electrodeposition bath to improve the appearance of the electrodeposited coatings. The additive comprises an ungelled reaction product of a polyepoxide and a polyoxyalkylenepolyamine. Although effective in improving appearance, this additive can cause problems of adhesion to subsequently applied materials especially alkyd topcoats to the electrocoats.
The present invention is an improvement in said additive whereby crater resistance of the coating is improved without causing the aforedescribed adhesion problems.